Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 1,326,478	$ 1,300,722
Finite-Lived Intangible Assets, Accumulated Amortization	54,982	47,747
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,837	$ 1,926
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, Authorized shares	5,000	5,000
Preferred stock, Shares issued	0	0
Preferred stock, Shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, Authorized shares	1,600,000	1,600,000
Common stock, Shares issued	417,356	425,390
Common stock, Shares outstanding	417,356	425,390